#app {
    border: dashed black 1px;
    display: inline-block;
    padding-bottom: 10px;
  }
  
  #app > button {
    display: block;
    margin: auto;
  }
  
  #lightDiv {
    position: relative;
    width: 150px;
    height: 150px;
  }
  
  #lightDiv > img {
    position: relative;
    width: 100%;
    height: 100%;
  }
  
  #lightDiv > div {
    position: absolute;
    top: 10%;
    left: 10%;
    width: 80%;
    height: 80%;
    border-radius: 50%;
    background-color: yellow;
  }